Prime Minister Rishi Sunak warned that there was a “growing consensus that mob rule is replacing democratic rule”.
Speaking at a roundtable of police chiefs, he said: “We cannot allow a pattern of increasingly violent and intimidating behavior” to prevent elected representatives from doing their jobs.
Mr Sunak did not clarify who he was referring to mob rule.
However, concern has increased in recent months about the safety of MPs since the outbreak of war in Gaza.
Sunak told police officers at the meeting in Downing Street that they needed to demonstrate to the public “that you will use the powers you already have” during a roundtable.
The government announced a new Democratic Police protocol, which Mr Sunak said commits to extra patrols and makes clear that protests at the homes of elected representatives should be treated as intimidation.
“I will do whatever it takes to protect our democracy and the values that we all hold dear,” he said.
“This is what the public expects. It is fundamental to our democratic system. It is also vital to maintaining public confidence in the police.”
Massive and largely peaceful demonstrations have taken place across the UK since the attacks by Hamas on Israel on 7 October, when Israel began its military offensive in response to the group's destruction in Gaza.
Home Secretary James Cleverley on Wednesday announced a £31 million package to boost protection for MPs, some of whom have spoken of being intimidated and harassed by pro-Palestinian supporters.
But Justice Secretary Mike Freer, who is stepping down at the next election over safety concerns, said the extra money “will not go to the root cause” of why people felt emboldened to target MPs.
He said that unless you deal with the issue, you will have a “ring of steel around the representatives” and then “our whole democratic style will change.”
One of the groups behind the demonstrations, the Palestine Solidarity Campaign, said it did not support protests outside MPs' homes but defended the right to hold peaceful protests outside MPs' offices and council chambers.
The war between Israel and Gaza broke out on October 7 when Hamas militants infiltrated southern Israel, killing about 1,200 people and taking 253 others hostage.
About 130 are still detained in Gaza.
At least 29,954 Palestinians have been killed, according to the Hamas-run Health Ministry in Gaza.
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